Method and device for buffering products

ABSTRACT

A method for buffering products, such as bottles, cans and pots, wherein the products are carried upwards on a moving, inclined first conveying surface at a first flow rate. The products on the first conveying surface can accumulate against a guide member at the upper end of the first conveying surface, after which the products are guided from the guide member onto a second conveying surface, on which they are conveyed onwards at a second flow rate. The first conveying surface is disposed at such an angle and is provided with such a surface condition that the dragging force exerted on the products from the first conveying surface is just a little greater than the force of gravity being exerted on the products in the direction along the conveying surface. As a result, the products can be buffered in a simple manner, while the products exert only little pressure on each other.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of buffering products, inparticular substantially cylindrical containers, such as bottles, cansand pots. The invention also relates to a device for carrying out thismethod.

2. Description of the Related Art

In many cases it is necessary to buffer products in a treatment line forproducts. For example, in a bottling plant, bottles must be filled,sealed, labelled and packaged. The handling rate may be temporarilyhigher or lower at different locations in the line, making it necessaryto buffer the bottles between two treatment locations in order toprevent having to adapt the entire treatment line temporarily.

Various methods of buffering products are known. One known methodemploys a conveyor comprising a forwardly moving conveyor belt and abackwardly moving conveyor belt, as well as a transfer device, whoselocation on the conveyor depends on the relative speeds of the twoconveyor belts. In this way a larger or smaller part of the conveyor isoccupied by the products, depending on the required buffering capacity.

Although this method is satisfactory per se, it requires a complexapparatus to ensure a smooth operation.

SUMMARY OF THE INVENTION

The object of the invention is to provide a comparatively simple methodfor buffering products.

In order to accomplish that object, the invention provides a method forbuffering products, in particular cylindrical containers, such asbottles, cans and pots, wherein the products are carried upwards on amoving, inclined first conveying surface at a first flow rate and theproducts on said first conveying surface can accumulate against a guidemember at the upper end, after which the products are guided from theguide member onto a second conveying surface, on which they are conveyedonwards at a second flow rate, wherein the first conveying surface isdisposed at such an angle and is provided with such a surface conditionthat the dragging force exerted on the products from the first conveyingsurface is slightly greater than the force of gravity being exerted onthe products in the direction along the conveying surface.

In principle, this method can be self-regulating, because the firstconveying surface is automatically filled with or cleared of products,depending on the rate at which the products are supplied and discharged.A suitable selection of the angle of inclination of the conveyingsurface and of the surface condition thereof makes it possible tocontrol the method so that the products are just carried upwards on thefirst conveying surface. The consequence of this is that the pressure onthe accumulating products can be kept low because the first conveyingsurface can easily move under the products and newly arriving productsare pressed against the accumulated products with only little force. Byselecting a specific lubrication, for example, it is possible to adjustsuch a coefficient of friction between the first conveying surface andthe products that are carried up-wards with the desired dragging forceon the first conveying surface.

The invention furthermore relates to a device for carrying out thismethod.

To obtain a large buffering capacity, the width of the first conveyingsurface will preferably be greater than the width of the secondconveying surface, and the conveying surfaces will be laterally boundedby guides.

In this way a large number of products can accumulate on the firstconveying surface, but the products will leave the buffering device oneby one via the second conveying surface, so that the products will besupplied for a new treatment at an even rate. To form a compact device,it is advantageous if the guide member extends at an angle with respectto the first conveying surface, being arranged for deflecting andpreferably reversing the flow of products, wherein said first and secondconveying surfaces are preferably formed on endless conveying elementsthat are driven in opposite directions, which are at least partially ledalong identical paths, which are preferably helical in shape.

In this way the device occupies a minimum amount of floor space, andconsequently the buffering area is extended in vertical direction, whereusually sufficient space is available.

Preferably, the device is provided with a lubricating device forlubricating the first conveying surface. Using this lubricating device,the coefficient of friction between the first conveying surface and theproducts to be buffered can be adjusted so that the products arecorrectly conveyed and accumulated by the device.

The invention will be explained in more detail hereinafter withreference to the drawings, which schematically show an embodiment of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view of an embodiment of the device forbuffering products according to the invention.

FIG. 2 is a top plan view of the device of FIG. 1.

FIG. 3 is a partial top plan view comparable to FIG. 2 of a device, alsoshowing the guide member.

FIG. 4 is a schematic top plan view of a device during operation, whichillustrates the buffering method according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The drawings show a device for buffering products. Said buffering takesplace in a processing line in which the products are subjected tovarious processing or treatment steps at various locations, and in whichtemporary differences in the processing rates at said locations must beset off. The products may consist of containers, for example, inparticular substantially cylindrical containers such as bottles, cans,pots and the like. In most cases the processing line consist of afilling line for filling the containers in question, such as a bottlingline for filling the bottles with a beverage. The buffering device maybe arranged between a depalletising station and a washing and/or fillingstation, between the filling station and a labelling station and betweenthe labelling station and a packaging station, for examples. Also otherfields of application are conceivable, of course.

The device as shown comprises a frame, in this embodiment having acentral column 1 with a base 3 and a helical guide chute 3 extendingaround the column and being attached thereto. Also, all kinds of otherframe constructions are conceivable, of course. An end roller 4, 5 isdisposed at the upper end and the lower end of the guide chute, and areturn chute 6 of the frame extends between said ends of the helicalguide chute 3. With the device according to the invention, the guidechute 3 and the return chute 6 support a first conveyor belt 7 and asecond conveyor belt 8. The conveying part and the return part of thetwo conveyor belts 7, 8 move along different paths. It is alsoconceivable to use an embodiment in which the return part is led backalong the bottom side of the guide chute 3 for the conveying part.

In the illustrated embodiment, the helical chute 3 comprises eightwindings, but it is possible to use a larger or a smaller number,depending on the application in question. By using guide rollers on theconveyor belts 7, 8, for example, the conveyor belts can be driven overa large number of windings without any driving problems. The twoconveyor belts 7, 8 each have their own driving motor 9, 10, whichmotors are disposed near the upper end roller 5, in this case, and whichengage the associated conveyor belt 7, 8. The two conveyor belts 7, 8can be driven independently of each other, in opposite directions in thepresent case, i.e. the products are conveyed upwards over the conveyingsurface of the first conveyor belt 7 as indicated by the arrow P₁, anddownwards again over the conveying surface of the second conveyor belt 8(see arrow P₂). At the location indicated by the arrow P_(1,2), theproducts are transferred from the first conveying surface of the firstconveyor belt 7 to the second conveying surface of the second conveyorbelt 8, preferably by means of a guide member 11 (see FIG. 3).

As FIG. 3 further schematically shows, guides 12, 13 are arranged oneither side of the guide chute 3, whilst the first conveyor belt 7 andthe second conveyor belt 8 are separated by an intermediate guide 14.The intermediate guide 14 extends upwards to a position in which it isspaced from the guide member 11 by some distance, which distance is justsufficiently large for allowing a product to pass from the firstconveyor belt 7 to the second conveyor belt 8. The intermediate guide 14and/or the guide member 11 may be adjustable in longitudinal directionso as to be able to buffer different kinds of products. The guides 12-14may also be adjustable for correctly guiding products having differentdiameters.

The guide member 11 that is provided near the upper end of the firstconveyor belt 7 may be stationary and consequently guide the productsonly passively from the first conveyor belt 7 to the second conveyorbelt 8. On the other hand, the guide member 11 may be driveable, i.e.movable so as to guide the products in a more active manner. Such amovement may be a circulating movement in the direction of the firstconveyor belt 7 to the second conveyor belt 8. For example, a beltguided by rollers may be arranged around the guide member 11. On theother hand, said movement may also be an oscillating movement in theplane of the conveyor belt 7, so as to prevent local blockages and thusaid the flow of products.

In the illustrated example, the first conveyor belt 7 has a greaterwidth than the second conveyor belt 8, and preferably the width of thesecond conveyor belt 8 is such that the buffered products can only betransported one behind another over the second conveyor belt 8. In thatcase, the products can be evenly supplied one by one to a treatmentlocation downstream of the device. In the illustrated case, the width ofthe first conveyor belt 7 is such that a number of products, e.g. fourto ten products, five in the illustrated embodiment, can be presentbeside each other on the conveying surface of the conveyor belt 7. Inthis way, the first conveyor belt 7 has a conveying surface with a largearea, and a large buffering capacity can be obtained because the devicecan accommodate a large number of products. The guides 12-14 may beadjustable so as to make it possible to adapt the device to thedimensions of the products.

Several embodiments of the first conveyor belt 7 are possible, as longas a preferably more or less closed surface having a sufficiently lowfriction is obtained. Examples of such conveyor belts are lamella belts,link belts, stainless steel lamella chains, textile belts, PVC belts,stainless steel belts and the like, which latter belt types aregenerally only suitable for use in a straight, i.e. non-curved conveyingpath. The invention also extends to devices comprising straightconveying paths, however.

The construction of the second conveyor belt 8 may vary, depending onthe kind of products and the requirements made of the discharge and thefurther transportation of the products (see the arrow D). In principle,a “wedge conveyor” or a “side grip conveyor” might be used, whilst alsothe path of the second conveyor belt 8 may be completely different fromthe illustrated path. Furthermore, the second conveyor belt need notextend downwards.

In practice, the angle at which the conveying surface of the firstconveyor belt 7 is disposed is generally 2-10°, in particular 3-6°,preferably 4-4.5°. This angle of inclination must be geared to theexpected coefficient of friction between the conveying surface of thefirst conveyor belt 7 and the products being transported. After all,according to the invention, the dragging force being exerted on theproducts from the conveying surface of the first conveyor belt 7 isintended to be greater than the force of gravity being exerted on theproducts in the direction along the conveying surface of the firstconveyor belt 7. In the case of a fixed angle of inclination, this canbe achieved by a suitable selection of the conveyor belt or byinfluencing the coefficient of friction, which is done by lubricatingthe conveying surface of the first conveyor belt 7. The coefficient offriction between the conveying surface and the product to be bufferedmay be 0.14-0.16, for example. Thus, the products to be buffered areonly just carried upwards on the conveying surface, and the products areprevented from exerting too much pressure on each other as soon as saidproducts accumulate at the end of the first conveying surface of theconveyor belt 7. Consequently, there is only a small chance of theproducts being damaged as a result of said pressure, whilst in additionsaid pressure will not lead to the products getting wedged upon beingtransferred to the second conveyor belt 8. Especially in the case ofcylindrical products this risk will be very small.

FIG. 4 shows an embodiment of the method according to the invention.Arrow S indicates a supply conveyor 15, at which products P are suppliedfrom a processing location and the guided onto the conveyor belt 7. Theconveying surface of the first conveyor belt 7 moves in the directionindicated by the arrow A, at a rate that ensures a correct transfer ofthe products P from the supply conveyor S and a sufficient flow ofproducts. The products P that are being supplied are carried along at arandom location on the conveying surface of the first conveyor belt 7towards the upper end thereof. Depending on the rate at which the secondconveyor belt 8 takes over products, a number of products willaccumulate, i.e. come to a virtual standstill, near the upper end of thefirst conveyor belt 7. Due to the low amount of friction and the lowdragging force being exerted on the bottom of the products P by theconveying surface, the pushing force that is exerted on the accumulatedproducts will only be low.

A guide member 11 is provided near the upper end of the first conveyorbelt 7, by means of which products P are transferred one by one from thefirst conveyor belt 7 to the second conveyor belt 8. Said transfer takesplace as a result of the pressure being exerted on the products P andthe preceding product P being discharged by the second conveyor belt 8.The guide member 11 may be driven so as to assist in the transfer of theproducts P. Depending on the difference between the amount of productsbeing supplied at S and the amount of products being discharged at D, alarger or smaller amount of products P will accumulate on the conveyingsurface of the first conveyor belt 7, so that a larger or a smaller partof the conveying surface will be occupied by the products.

It will be apparent from the foregoing that the invention provides asimple method and device for accumulating products.

The invention is not limited to the embodiments as described above andillustrated in the drawings, which can be varied in several ways withinthe scope of the invention. Thus, the guide member need not be disposednear the upper end of the first conveyor belt. Furthermore, it ispossible for the guides present on either side of the first conveyorbelt to move along with said conveyor belt. No intermediate guide mustbe present at the transfer location between the first and the secondconveyor belt, however, or the intermediate guide must be present belowthe surface of the conveyor belts. The second conveyor belt may extendalong a path completely different from that of the first conveyor belt.Thus the second belt may extend in the same direction as the first belt,with a guide member preferably guiding the products laterally from thefirst conveyor belt to the second conveyor belt. Furthermore, the firstand/or the second conveyor belt may be built up of several narrow beltsarranged side by side. Said belts may be driven at slightly differentspeeds, but preferably in the same direction and synchronously inrelation to each other. Such a driving technique makes it possible toprevent or, on the contrary, stimulate a lateral flow of products on theconveyor belts, depending on the application in question. Both the firstand the second conveyor belt may be suitable for conveying one or moreproducts beside each other. The two conveyors may be driven in differentways. Independent drive units and electronically or mechanically coupleddrive units may be used.

The invention claimed is:
 1. A method of buffering products, in particular substantially cylindrical containers, said method comprising carrying the products upwards on a moving, inclined first conveying surface at a first flow rate towards a guide member for transferring the products from the first conveying surface to a second conveying surface, the guide member being disposed adjacent an upper end of the first conveying surface, such that the products on the first conveying surface can be stopped by and accumulate against the guide member, and guiding the products from the guide member onto the second conveying surface, and conveying the products onwards on the second conveying surface at a second flow rate, the second flow rate being different from the first flow rate, wherein in said carrying of the products upward on the first conveying surface, the first conveying surface is inclined at an angle and is provided with a surface condition such that the dragging force exerted on the products from the first conveying surface is greater than the force of gravity being exerted on the products in a direction along the first conveying surface, so as to allow the products to move relative to the first conveying surface as the first conveying surface carries the products upwards.
 2. The method according to claim 1, wherein several of the products are transported beside each other on the first conveying surface, whilst the products are transported one behind another on the second conveying surface.
 3. The method according to claim 1, wherein said guiding comprises changing the direction of the products at the guide member, such that the products are transported in opposite directions over at least part of their conveying path on the first and the second conveying surfaces.
 4. A device for buffering products, in particular substantially cylindrical containers, such as bottles, cans and pots, said device comprising a drivable, inclined first conveying surface for carrying the products upwards at a first flow rate, the first conveying surface having an upper end, a drivable second conveying surface for transporting the products, a guide member for stopping the products on the first conveying surface and for transferring the products from the first conveying surface to the second conveying surface, so that the products can accumulate against the guide member and be guided from the guide member onto the second conveying surface, said guide member being positioned at the upper end of the first conveying surface, and the second conveying surface being configured for transporting the products onwards from said guide member, wherein said first conveying surface is inclined at an angle and has a surface condition such that the dragging force exerted on the products from said first conveying surface is greater than the force of gravity exerted on the products in a direction along said first conveying surface, so as to allow the products to move relative to the said first conveying surface as said first conveying surfaces carries the products upwards.
 5. The device according to claim 4, wherein said first and second conveying surfaces each have a width, and the width of said first conveying surface is greater than the width of said second conveying surface, and wherein said conveying surfaces are laterally bounded by guides.
 6. The device according to claim 4, wherein said guide member is arranged at an angle with respect to said first conveying surface for deflecting and or reversing the products.
 7. The device according to claim 6, wherein said first and second conveying surfaces are formed on endless conveying elements that are driven in opposite directions, said conveying elements having at least partially identical helical paths.
 8. The device according to claim 4, wherein said guide member can be driven to guide the products toward said second conveying surface.
 9. The device according to claim 4, further comprising a lubricating device for lubricating said first conveying surface.
 10. The device according to claim 4, wherein said first conveying surface is inclined at an angle in a range of 3° to 6°, and the coefficient of friction between said first conveying surface and the products is in a range of 0.14-0.16.
 11. A product treatment line comprising a supply conveyor, a discharge conveyor, and a device for buffering products, said device for buffering products comprising a drivable, inclined first conveying surface for carrying the products upwards at a first flow rate and having an upper end, a drivable second conveying surface for transporting the products, a guide member for stopping the products on the first conveying surface and for transferring the products from the first conveying surface to the second conveying surface, so that the products can accumulate against the guide member and be guided from the guide member onto the second conveying surface, said guide member being positioned at said upper end of said first conveying surface, and the second conveying surface being configured for transporting the products onwards from said guide member, wherein said first conveying surface is inclined at an angle and has a surface condition such that the dragging force exerted on the products from said first conveying surface is greater than the force of gravity exerted on the products in a direction along said first conveying surface, so as to allow the products to move relative to said first conveying surface as said first conveying surface carries the products upwards.
 12. The method according to claim 2, wherein said guiding comprises changing the direction of the products at the guide member, such that the products are transported in opposite directions over at least part of their conveying path on the first and the second conveying surfaces.
 13. The device according to claim 5, wherein said guide member is arranged at an angle with respect to said first conveying surface, for deflecting or reversing the products.
 14. The device according to claim 13, wherein said first and second conveying surfaces are formed on endless conveying elements that are driven in opposite directions, said conveying elements having at least partially identical helical paths.
 15. The device according to claim 5, wherein said guide member can be driven to guide the products toward said second conveying surface.
 16. The device according to claim 6, wherein said guide member can be driven to guide the products toward said second conveying surface.
 17. The device according to claim 13, wherein said guide member can be driven to guide the products toward said second conveying surface.
 18. The device according to claim 7, wherein said guide member can be driven to guide the products toward said second conveying surface.
 19. The device according to claim 14, wherein said guide member can be driven to guide the products toward said second conveying surface.
 20. The device according to claim 5, further comprising a lubricating device for lubricating said first conveying surface.
 21. The method of buffering products according to claim 1, wherein in said carrying of the products upwards on the first conveying surface, the first conveying surface is inclined at an angle in a range of 3° to 6°, and the coefficient of friction between the first conveying surface and the products is in a range of 0.14-0.16.
 22. The product treatment line according to claim 11, wherein said first conveying surface is inclined at an angle in a range of 3° to 6°, and the coefficient of friction between said first conveying surface and the products is in a range of 0.14-0.16. 